Biplane x-ray image system



April 22, 1969 BALL ET AL BIPLANE X-RAY IMAGE SYSTEM Filed June 24, 1965United States Patent Office 3,440,422 Patented Apr. 22, 1969 3,440,422BIPLANE X-RAY IMAGE SYSTEM Jack Ball, Chesterland, and Gunter G.Wilkens, Wicklilfe,

Ohio, assignors, by mesne assignments, to Picker Corporation, WhitePlains, N.Y., a corporation of New York Filed June 24, 1965, Ser. No.466,725 Int. Cl. H05g 1/00; G01n 23/04; H01j 37/22 US. Cl. 250-93 17Claims ABSTRACT OF THE DISCLOSURE In a biplane system employing aplurality of X-ray tubes and associated image amplifier tubes, theindividual combinations of X-ray and amplifier tubes are alternatelyturned on and off, so that each amplifier tube responds to andintensifies radiation only from its associated X-ray tube when thelatter is also turned on.

Mechanical shutters are not required on cameras photographing theintensified images, and film is transported in each camera while itsassociated image intensifier and X-ray tubes are turned off.

The present invention relates to X-ray systems and more particularly tobiplane X-ray apparatuses.

In medical studies of the conditions of parts or organs of the humanbody, particularly for diagnostic purposes, it is sometimes desired andoftentimes necessary to make X-ray film exposures of the body parts ororgans from both a frontal or nearly frontal direction, generallyreferred to as an anterior-posterior or AP exposure, and a side ornearly side direction at right angles to the frontal direction generallyreferred to as a lateral exposure.

Biplane X-ray systems generally comprise two separate X-ray systems eachhaving an X-ray tube and an X-ray sensitive film or other X-ray exposureimage receiver positioned on the side of the body opposite of the sourceof X-rays, i.e., the X-ray tube. The path or beam of the X-rays from oneX-ray tube through the body or subject to its associated image receiveris therefore at right angles to the beam of X-rays in the other X-raysystem so that one is used for making AP exposures and the other is usedfor making lateral exposures.

In such biplane systems, the AP and lateral exposures are generally madeat different intervals, i.e., alternately, to avoid exposing the patientto large simultaneous doses of X-rays and to prevent one X-ray tubesystem from interferring with the other system so as to achieve maximumclarity and sharpness in their respective film images. Prior systemshave operated the AP X-ray tubes and image receivers alternately withthe lateral X-ray tubes and image receivers. The alternate operation maycomprise a rapid sequence of film exposures as in cine wherein aplurality of AP and lateral film images are recorded in rapid alternatesequence by AP and lateral cameras. In these cine systems, the lens ofeach camera is focused on the output phosphor of an associated imageintensifier tube which is interposed between the subject and the camerato intensify the X-ray image passed to the film of the camera each timethe camera shutter opens.

In many biplane systems using image intensifier or amplifier tubes,phototubes are provided and are focused on the output phosphors of theimage amplifier tubes. The

phototubes are connected to suitable control circuits which adjust thebrighteness of the images on the output phosphors to maintain a uniformbrightness of the images presented to the cameras.

These prior biplane systems have experienced several problems which areattributable to extraneous X-rays scattering from one X-ray system intothe other and to a storage effect in the image amplifier tubes. Theinputs phosphors of the image amplifier tubes each receive primaryradiation directly through the subject from its associated X-ray tubeand secondary radiation which is extraneous scattered radiation from theother X-ray tube. Forexample, the lateral image amplifier receivesprimary radiation from the lateral X-ray tube during energization of thelateral X-ray tube and secondary radiation from the AP X-ray tube whenthe AP X-ray tube is energized.

The image amplifier tube has a retentive characteristic which tends tostore or retain an image and emit it from its output phosphor after aprimary X-ray beam is no longer incident upon its input phosphor. Inaddition, in any prior biplane system, one X-ray tube will interferewith the operation of the image tube of the other system. For example,when the lateral X-ray tube is energized after the AP X-ray system hasbeen in operation, the image of the lateral image amplifier tube isalfected by what might be described as a noise image produced bysecondary radiation from the AP system. Thus, after the lateral X-raytube is shut off, the image emitted by the output phosphor of thelateral image tube is initially continuous relatively bright anddiminishes gradually. The noise image from scatter radiation from the APimage is superimposed on the retained image from the primary radiation.The noise image fogs film used to photograph the output phosphor and, inaddition, the retained image blurs the photographic image because thefilm is moved at the time when the primary beam is shut olf.

In the X-ray system having brightness control, the phototubes lookinginto the image amplifier tubes register the excessive brightness fromthe scattered radiation and the retained primary radiation in additionto the primary radiation. The automatic brightness control circuits donot, therefore, function properly to control the brightness of theimages seen by the cameras looking at the output phosphors.

In the present system, these problems are circumvented by controllingoperation of the image amplifier tube so that the image tubes functionas electronic shutters in addition to intensifying the desired images.In the present system, photocathodes of the image amplifier tubes areinitially biased several hundred volts positive relative to groundpotential to prevent an electron flow through the image amplifier tubesto the output phosphors at its anodes and thereby turn the image tubesas electronic shutters off. The image amplifier tubes are turned on aselectronic shutters preferably by clamping the photocathodes to theground potential.

It has been found that by placing the image amplifier tubes normally ina cut-off state to provide effectively closed shutters, no electrons canleave the photocathodes and reach the anodes. Thus, no electronstraverse the image amplifier tubes. The light output of the inputphosphor from scatter radiation incident on the input phosphor of thecut-off or closed image tube of one system during operation of the othersystem is substantially completely dissipated by the cutoff image tubeby the time it later opens to receive incident primary radiation as whenits system is in operation and the other system is cut-off. In additiona latent image remaining after the image tube was shut off at thetermination of a previous pulse is dissipated during the off period.Tests indicate that there is no interference with the dissipation of thelatent and noise images.

In the present system, by utilizing the image amplifier tubes aselectronic shutters as well as intensifiers, the conventional mechanicalshutters of the cameras are not required. The cameras are continuouslyopen and are focused in light tight relation on the output phosphors ofthe image tubes. A suitable control system is provided for co-ordinatingthe shutter operation of the image amplifier tubes to the operation offilm transport mechanisms in the cameras and to the energization of theX-ray tubes. The X-ray tubes are energized when the electronic shuttersare turned on. The camera films are transported to new frame positionsafter the shutters are turned off. The control system alternatelyoperates the AP and lateral X-ray systems so that, for example, the APX-ray tube and electronic shutter are turned on when the lateral X-raytube and electronic shutter are turned off.

In lower frame rate settings (i.e., frames per second) clutches in thefilm transport mechanisms are operated upon closure of the shutters tomove the film for the next X-ray exposures. In high film rateapplications, the cameras are caused to run continuously and theelectronic shutters open and close in a synchronized, alternate relationwith each other and in synchronism with the energization andde-energization of the X-ray tubes. Different exposure times, i.e., theduration of the X-rays, for the different frame rates are provided bycontrolling the duration of the energization of the X-ray tubes for eachframe exposure. In the frame rate settings equal to line frequency theexposure time is provided by opening opposite sets of half waverectifiers in bridge rectifier circuits located in the X-ray tubeenergization circuits so that the X-ray tubes are pulsed alternately byhalf wave rectified voltages.

In the present system, a high voltage flip-flop circuit is used tosynchronize the operation of the image tubes, the cameras and theenergization of the X-ray tubes. The high voltage flip-flop circuit hasone of its outputs connected to control the shutter operation of the APimage amplifier tube and the other output connected to control theshutter operation of the lateral image amplifier tube. Since one outputis always on when the other is off, the flip-flop automatically operatesthe image amplifier'tubes alternately as shutters in proper biplanerelation. The opening and closing of the electronic shutters are delayedslightly so as to coincide exactly with the energization of the X-raytubes which is delayed by the high voltage trans formation circuits inthe X-ray tube energization systems.

Accordingly, an object of the present invention is to provide a new andimproved biplane X-ray system.

Another object of the present invention is to provide a new and improvedX-ray system wherein an image intensifier tube is operated as anintensifier and as an electronic shutter.

And another object of the present invention is to provide a new andimproved biplane X-ray system wherein image amplifier tubes aremaintained in cut-01f condition during the periods that their respectiveX-ray tubes are de-energized to prevent the transfer of images incidenton their input phosphors to the output phosphors and are turned on topermit electron conduction to their output phosphors when theirrespective X-ray tubes are energized for X-ray exposures.

Still another object of the present invention is to provide a new andimproved biplane X-ray system wherein the image intensifier tubes areoperated as electronic shutters as well as intensifiers and are operatedalternately with the energization of their respective X-ray tubes in adelayed manner to coincide exactly with the energization of the X-raytubes.

Yet another object of the present invention is to provide a new andimproved biplane X-ray system wherein the image amplifier tubes functionas electronic shutters which are opened and closed in alternate relationby alternate states of energization of a single switching device.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims taken in conjunctionwith the accompanying drawings in which:

FIGURE 1 is a schematic drawing using block diagrams of the biplaneX-ray tube energization and shutter control systems of the presentinvention.

FIGURE 2 is a detailed circuit drawing of an X-ray tube energizationcircuit from the systems of FIGURE 1.

FIGURE 3 is a schematic circuit drawing of a frame rate and exposuretime selector control system for the systems of FIGURE 1.

FIGURE 4 is a front view of a selector panel for the selector system ofFIGURE 3.

FIGURE 5 is a detailed circuit drawing of the systems of FIGURE 1.

Referring now to FIGURE 1, a biplane X-ray system includes ananterior-posterior (hereinafter referred to as AP) X-ray tube system 22and a lateral X-ray tube system 23. The AP and lateral X-ray tubesystems 22, 23 are substantially identical and like reference charactersdesignate like parts in both systems with an additional referencecharacter A being added to the numerical reference characters in the APsystem 22 and an additional reference character L added to the numericalreference character designating parts in the lateral system 23.

The AP and lateral X-ray tube circuits are identical and include X-raytubes 25A, 25L supplied from the same voltage source e through voltagecontrol circuits 26A, 26L which set the voltage levels supplied to theX-ray tubes, electronic contactor circuits 27A, 27L for controllingenergization of the X-ray tubes, and high voltage t-ransformer andrectifier circuits 28A, 28L for stepping up the voltage levels andrectifying them to supply DC kilovoltages to the X-ray tubes. Thedetails of both X-ray tube circuits are shown by the single X-ray tubecircuit in FIGURE 2. The various parts of the X-ray tube circuit ofFIGURE 2 are designated by numerical reference characters only forgeneral description purposes here, it being understood that the samepar-ts are designated by the additional reference characters A, L whendescribed in connection with the AP and lateral systems respectively.For example, the X-ray tube is designated by the reference character 25in FIGURE 2, by the reference character 25A in connection with the APX-ray tube circuit, and by the reference character 25L in connectionwith the lateral X-ray tube circuit.

The voltage control circuit 26 includes an autotransformer 29 having itsinput terminals connected across the AC voltage source e and its outputvoltage taps 30, 31 connected to a primary winding 32 of a high voltagetransformer in the transformer and rectifier circuit 28. The secondarywinding 34 of the high voltage transformer 33 is connected to the inputside of a full wave rectifier circuit 35 via conductors 36, 37. Theoutput terminals of the full wave bridge rectifier circuit 35 areconnected to the anode and cathode elements of the X-ray tube 25 viaconductors 38, 39. Thyratron tubes 40, 41 in the electronic contactorcircuit 27 are connected back-to-back between the primary winding 32 ofthe high voltage transformer 33 and the secondary tap terminal 31 of theautotransformer 29. As will be explained, the electronic contactorcontrol circuit 27 controls conduction of the thyratron tubes 40, 41which in turn control energization of the X-ray tube 25 from the voltagesource e.

As is shown by the drawing (FIGURE 1), the AP and lateral X-ray tubes25A, 25L are positioned so that their X-ray beams impinge on a subject46, e.g., a human body, at right angles to one another. The X-ray beamfrom the AP X-ray tube 25A impinge on the subject 46 so as to provide ananterior-posterior exposure. The X-ray beam from the lateral X-ray tube25L impinge on the subject 46 so as to provide a lateral X-ray exposure.

The X-ray systems 22, 23 further include AP and lateral image amplifiertubes 47A, 47L, and AP and lateral cine cameras 48A, 48L having theirlenses focused in light tight relation on output phosphor screens oftheir associated image amplifier tubes 47A, 47L, respectively. The APimage tube 47A and the AP cine camera 48A are positioned in alignedrelation with the X-ray beam from the AP X-ray tube A and on theopposite side of the subject 46 from the AP X-ray tube 25A. The lateralimage amplifier tube 47L and the lateral cine camera 48L are arranged ina similarly aligned relation with the X-ray beam from the lateral X-raytube 25L and on the opposite side of the body 46 from the lateral X-raytube 25L. The aligned lateral X-ray system is at right angles to thealigned AP X-ray system. The input phosphor of the AP image tube 47Areceives primary X-ray radiation from the output of the AP X-ray tube25A and secondary radiation from the output of the lateral X-ray tube25L. The input phosphor of the lateral image amplifier tube 47Lsimilarly receives primary radiation from the lateral X-ray tube 25L andsome secondary radiation from the AP X-ray tube 25A. The image amplifiertubes intensify images presented to their input phosphors and displaythe intensified images on their output phosphors. As will be explained,the image amplifier tubes 47A, 47L are controlled to function also aselectronic shutters for the cine cameras 48A, 48L. The cine cameras 48A,48L do not have the conventional camera shutters.

The electronic contactors 27A, 27L are turned ON to energize theirrespective X-ray tubes by control signals from AP and lateralmultivibrators 54A, 54L, respectively. Operation of the multivibrators54A, 54L is controlled by a frame rate and exposure time selectorcircuit 58 via lines 55A, 55L. The frame rate and exposure time selectorcircuit 58 also controls operation of the AP and lateral image tubes47A, 47L and cameras 48A, 48L in synchronism with energization of theX-ray tubes through a shutter and camera control circuit 60 .The shutterand camera control circuit 60 has its input connected to the frame rateand exposure time selector circuit 58 via conductor 61 and its outputsconnected to the image amplifier tubes 47A, 47L via conductors 62A, 62Land to the cameras 48A, 48L via conductors 63A, 63L.

The frame rate and exposure time selector circuit 58 sends controlsignals alternately to the multivibrators 54A, 54L via conductors 55A,55L so that the electronic contactors 27A, 27L are energized alternatelyto cause the AP and lateral X-ray tubes 25A, 25L to be energized and toprovide AP and lateral exposures alternately. The selector circuit 58also provides a control signal to the shutter and camera control circuit60 via conductor 61 for each control signal provided to the AP andlateral multivibrators 54A, 54L, respectively. The lengths of thesecontrol signals and their frequency is determined by an exposure timeand a frame rate set on a selector control panel 230 (FIGURE 4) for theselector circuit 58.

The shutter and camera control circuit 60 includes an amplifier circuit70 having its input connected to the conductor 61 and two outputsconnected to the first and second inputs respectively of a high voltageflip-flop 71 via conductors 72, 73. First and second outputs of theflip-flop 71 are connected to the image amplifier tubes 47A, 47L via theconductors 62A, 62L, respectively. The outputs of the amplifier 70 arealso connected to the inputs of AP and lateral camera clutch triggercircuits 75A, 75L via conductors 74A, 74L, respectively. The outputs ofthe trigger circuits 75A, 75L are connected to clutch mechanisms of thecine cameras 48A, 48L via the conductors 63A, 63L.

The amplifier 70 provides an output signal on control conductor 72 inresponse to a voltage signal above a predetermined level on conductor 61and an output signal on conductor 73 when the voltage signal onconductor 61 falls below such predetermined level. An output signal onconductor 72 from the amplifier 70 triggers, the high voltage flip-flopto turn the AP image tube on and the lateral image tube off and causesthe AP camera clutch trigger to send a film transport signal to thecamera at the termination of the output signal from the amplifier 70. Anoutput signal on conductor 73 from the amplifier 70 triggers theflip-flop 71 to turn the lateral image tube on, the AP image tube off,and causes the lateral camera clutch trigger circuit to send a filmtransport signal to the camera 48L at the termination of the controlsignal. Hence, the shutter control circuit 60 causes energization of theAP image tube and camera 47A, 48A in response to one control signal onconductor 61 and then energization of the lateral image tube and camera47L, 48L in response to the next control signal on conductor 61. Thefirst such control signal on conductor 61 corresponds to a controlsignal supplied to the AP multivibrator 54A. The next control signal onconductor 61 corresponds to a control signal supplied to the lateralmultivibrator 54L. The image tubes 47A, 47L are therefore operated insynchronism with the operation of the electronic contactors 27A, 27L sothat the AP image tube is shutter operated to provide an image to itsoutput phosphor at the time the AP X-ray tube is energized and thelateral image tube is shutter operated to pass an image to its outputphosphor when the lateral X-ray tube is energized. The shutter andcamera control circuit 60 further operates film transport mechanisms inthe cine cameras 48A, 48L alternately andafter their respective imageamplifier tubes have been turned off to transport their films to thenext frame position so as to position unexposed portions of the film inthe cameras fields for the next exposure.

Referring to FIGURE 2, the multivibrators 54A, 54L are each conventionalastable multivibrators which generate high frequency voltages, which arerectified by bridge rectifiers 98, 99, whenever the voltage level onconductors 55A, SSL is above a predetermined level. The DC outputvoltages on conductors 100403 are applied to diodes 104, 105 to reversebias them, thereby permitting the thyratron tubes 40, 41 to conduct andpass current to the transformer 28.

For example, batteries 106, 107 and the secondary windings of isolatingtransformers 108, 109 provide bias voltages to the control grids of thetubes 40, 41 which vary from a negative volts to a positive 30 volts atthe line frequency of voltage source "e". When the bias voltages gopositive, conduction of the tubes 40, 41 is prevented by the diodes 104,105 which are forward biased by the positive bias voltages and clamp thecontrol grids to the negative 30 volts of the batteries 106, 107.Rectified voltages of volts are provided by output conductors 100-103 ofthe multivibrators 54 in response to an input start trigger signal andare applied across resistors 110, 111 in the polarity shown to reversebias diodes 104, thereby releasing the clamp and permitting the tubes40, 41 to fire alternately at line frequency to pass the supply voltageto the transformer 28.

The rectifier circuit 35 includes four rectifier tubes 121- 124 arrangedin a bridge circuit. Energization of the cathodes of the tubes 121-124and hence conduction by the tubes is controlled by switches 125, 126which connect isolation transformers 129-132 to the voltage source e. Ifeither switch 125 or switch 126 is open and the other is closed so thatonly one set of rectifier tubes is on, then a half wave rectifiedvoltage is supplied to the X-ray tube 25 and effectively pulses theX-ray tube sixty times per second. Alternate biplane operation of theX-ray tubes is accomplished by turning different sets of the rectifiertubes off in the AP and lateral systems respectively so that one X-raytube is on when the other X-ray tube is off.

Referring to FIGURE 3, the frame rate and exposure time selector circuit58 includes a counter circuit 200 having an input conductor 201connecting a phase shift circuit 202 to the alternating current voltagesource e. The phase shift circuit 202 includes a phase shifting element203 for shifting the phase of its output relative to the phase of itsinput. The output of the phase shift circuit 202 is connected to theinput of a Schmitt trigger 205 via a conductor 204. The Schmitt trigger205 is conventional and converts the sine waves introduced at its inputvia conductor 204 to square waves at its outputs connected to conductors206, 207. A suitable Schmitt trigger comprises two transistors (notshown) arranged in a conventional regenerative bistable circuit. Thefirst output of the Schmitt trigger 205 (connected to the conductor 206)is from the collector of one transistor and provides a positive squarewave pulse for the negative half cycle of a sine wave introduced at itsinput on the conductor 204. The second output of the Schmitt trigger 205is from the collector of the second transistor and produces a positiveSquare wave for the postive half cycle of the sine wave introduced atits input via conductor 204. The conductors 206, 207 from the first andsecond outputs of the Schmitt triggers are connected to 60 pulses persecond selector conductors 208, 209, respectively. As line voltage issupplied to the input of the Schmitt trigger, a series of positivesquare wave pulses are produced alternately at the rate of 60 pulses persecond on each of the conductors 208, 209. I

A conductor 210 connects the second output of the Schmitt trigger 205 tothe input of the first of three flipflops 211-213 interconnected as acounter with the second outputs of the flip-flops 211, 212 connected tothe inputs of the flip-flops 212, 213 via conductors 214, 215,respectively. The flip-flops 211-213 are conventional bistablemultivibrators with positive steering diodes (not shown) connected inthe T-arrangement shown for base triggering. First and second outputsare taken from the collector elements of two transistors (not shown) ineach flip-flop circuit. Suitable differentiating devices (not shown) areinterposed in the conductors 210, 214 and 215 to change the square wavepulse outputs of the Schmitt trigger and the flip-flops 211, 212 topositive trigger pulses which are passed by the positive steering diodesof the flip-flops.

First and second outputs of the flip-flop 211 each provide 30 pulses persecond and are connected to 30 pulses per second selector conductors216, 217, respectively. First and second outputs of the flip-flop 212each provide 15 pulses per second and are connected to the 15 pulses persecond selector conductors 218, 219, respectively. The outputs of theflip-flop 213 each provide 7 /2 pulses per second and are connected to 7/2 pulses per second selector conductors 220, 221, respectively. Theoutputs of the Schmitt trigger 205 and of the multivibrators 211- 213provide their respective pulsed outputs to the conductors 208, 209 and216-221 as long as line voltage is supplied to the input conductor 201.

The pulsed output supply conductors 208, 209 and 216-221 are connectedto the combined frame rate and exposure time selector unit 230 which hasits front panel shown in FIGURE 4. The front panel of the selector 230includes a pointed indicator 231 which is positionable at any one ofsever-a1 terminal positions a through k, each of which provides adifferent combination of frame rates, i.e., the number of frames of filmexposed per second, and exposure time per frame expressed in the numberof cycles of the line voltage a per frame. The terminals (1- are forcine operation wherein the system runs continuously making exposures atthe frame rate selected with equal exposure times for each frame. Forexample, when the indicator 231 is positioned all the way counterclockwise to terminal a, the X-ray system will provide AP and lateralexposures each at the rate of 60 frames per second, each exposure timebeing /2 cycle of the incoming line frequency or one hundred-twentiethof a second. Terminals b and each provide a film rate of 30 frames persecond with terminal [1 providing a one cycle exposure time and terminal0 providing a half cycle exposure time. Terminals d and e provide a filmrate of 15 frames per second with terminal d providing an exposure timeof two cycles per frame and terminal e providing a half cycle ofexposure time per frame. Turning the selector indicator 231 to eitherterminal or g will provide a frame rate of 7 /2 frames per second withterminal f providing an exposure time of 4 cycles per frame and terminal3 providing an exposure time of a half cycle per frame.

The terminals h-k provide several different exposure times for singleframe operation of the X-ray tube system. The selector 231 is turned toone of the terminals h-k when the AP and lateral X-ray exposures aretaken one set at a time, each set being separately initiated. As shownby the drawing, terminals h-k represent exposure time values of /2, 1, 2and 4 cycles, respectively.

Referring again to FIGURE 3, the frame rate and exposure time selector230 has six selector switches 230a- 230 Each of the selector switches230a-230f includes terminals a-k which correspond in position to theterminals a-k on the face panel of the selector unit 230. The selectorswitches 23011-230 include movable contacts 231a-231 which are allganged together and to the selector indicator 231 as is indicated by thebroken line 232. Positioning the indicator 231 at one of the terminalsa-k also moves the movable contacts 231a-231c to a correspondingterminal in each of the switch banks 23011-230 The'three selectorswitches 230a-230c on the left side of the drawing are for selectingframe rates and exposure times for the AP X-ray system 22. The threeswitches 23011-230 on the right side of the drawing are for selectingfilm rates and exposure times for the lateral X-ray system 23.

The first switches 23011, 23011 in the AP and lateral switch groups arestart trigger switches for producing starting trigger signals whichinitiate closure of the electronic contactors 27A, 27L for energizationof the X-ray tubes and also initiate opening of the image tubes'47A, 47Las electronic shutters to provide an image to the cameras. The secondswitches 230b, 230e in the AP and lateral switch groups are shutterclosed switches for timing the length of time the electronic shutterremains open and produce shutter closed signals at the end of theexposure time. The third switches 230e, 230 in the AP and lateral switchgroups are exposure stopped switches and determine the period that theelectronic contactors remain closed and consequently the period forwhich the X-ray tubes are energized. The exposure stop switches 230e,230 produce an exposure stop signal at the end of the exposure time setby the selector switch indicator 231.

The movable contacts 231a-231f are each connected to a fixed contact235a-235f of an OVTV (optical viewingtelevision) and CINE selectorswitch indicated by the broken line 236. The OV-TV and CINE selectorswitch 236 includes fixed contacts 237a-237f connected to the aterminals of the selector switches 230a-230f and movable contacts23811-238 The contacts 23811-238 are movable as a unit to an OVTVposition engaging fixed contacts 23711-237 or to a CINE positionengaging fixed contacts 235a-235f.

The terminals a-k of the switches 230a-230f are connected to the pulsedoutput supply conductors 208, 209, 216-221 from the Schmitt trigger 205and the flip-flops 211-213 so as to provide the frame rates and exposuretimes shown on the face panel in FIGURE 4. The 60 frame rate terminals aof the AP and lateral shutter open or start trigger control switches23011, 23011 receive 60 square wave pulses per second from the secondoutput of the Schmitt trigger 205 via conductor 209. The 60 frame rateterminals a of the AP and lateral shutter closed selector switches 230b,2302 receive 60 square wave pulses per second from the first outputterminal of the Schmitt trigger 205 and therefore are out of phase by ahalf cycle with the pulses received by the a terminals of the starttrigger switches 230a, 2301!.

The 30 frames per second terminals b and c in the AP start triggerselector switch 230a and in the lateral shutter closed selector switch230e receive 30 square wave pulses per second from the first output ofthe flip-flop 211 while the 30 frames per second selector terminals band c in the AP shutter closed selector switch 230b and in the lateralstart trigger selector switch 230d receive 30 square wave pulses persecond from the second output of the fiip-fiop 211. The 15 frames persecond cine terminals a' and e and single frame selector terminals h, i,and i of the AP start trigger switch 230a and of the lateral shutterclosed selector switch 230s receive 15 square Wave pulses per secondfrom the first output of the flip-flop 212 While the correspondingterminals of the AP shutter closed selector switch 230b and of thelateral start trigger selector switch 230d receive 15 pulses per secondfrom the second terminal of the flip-flop 212 via conductor 219. The 7/2 frames per second selector terminals f, g, and the four cycle singleframe terminals k of the AP start trigger selector switch 230a and ofthe lateral shutter closed selector switch' 230:: receive 7 /2 squarewave pulses per second from the first output of the flip-flop 213 whilethe corresponding terminals in the AP shutter closed selector switch230b and in the lateral start trigger switch selector switch 230a'receive 7 /2 pulses per second from the second output of the flip-flop213.

The AP and lateral exposure stopped selector switches 230e, 230f havehalf cycle exposure time terminals connected through normally off AP andlateral gates 234A, 234L respectively to the second output of theSchmitt trigger 205 via the conductor 209 so that the terminals areceive exposure termination signal pulses at half cycle intervalsthrough the gates 234A, 234L which are normally turned on. The controlinputs of the gates 234A, 234L are connected to the control inputs ofnormally otf AP and lateral gates 241A, 241L via conductors 233A and233L, respectively.

The one cycle exposure time terminal b of the AP exposure stoppedselector switch 230a is connected to the second output of the 30 pulsesper second flip-flop 211 via conductor 217. The corresponding terminal bin the lateral exposure stopped selector switch 230 is connected to thefirst input of the flip-flop 211 via conductor 216. These terminals bthus receive exposure termination signal pulses at one cycle intervalsin an opposite phase relation. The half cycle exposure time terminals c,e, g and h and the one cycle terminal i of the AP and lateral exposurestopped selector switches 230c, 230f are connected to the second outputof the Schmitt trigger 205 and receive exposure termination signals athalf cycle intervals.

The two cycle exposure time terminals d and j of the AP exposure stoppedselector switch 230s are connected to receive exposure stop ortermination signal-pulses at two cycle intervals from the second outputof the flipfiop 212 via conductor 219 and the corresponding terminals inthe lateral exposure stopped selector switch 230 are connected toreceive exposure termination signal pulses at two cycle intervals fromthe first output of the flip-flop 212. The four cycle exposure timeterminals 1 and k of the AP selector switch 2300 are connected to thesecond output of the flip-flop 213 to receive pulses at four cycleintervals. The corresponding four cycle terminals f and k in the lateralexposure stopped selector switch 230 are connected to the first input ofthe flipfiop 213 and receive pulses at four cycle intervals in phasespaced relation, i.e., out of phase, to the four cycle pulses receivedby the AP exposure terminals 1 and k.

Positioning the selector indicator 231 to one of the terminals a-k, forexample at the two cycle terminal d, will result in control pulsesappearing on the conductors 252A, 252L at intervals corresponding to theselected exposure time, two cycle intervals in the example given. Thephase relationship of the exposure termination signal pulses on thelateral conductor 252L will always be out of phase to the signal pulseson the AP conductor 252L except when terminal a is selected. If terminala is selected the signal pulses on conductors 252A, 252L are in phase.

When the selector switches 23041-2301 are set by the selector controlindicator 231 to a particular frame rate setting, a shutter open signalappearing on the conductor 2440A from the AP trigger selector switch230a is followed by a delayed shutter closed signal on AP conductor 246Asuch that the number of cycles delay between the signals provides theframe rate selected. For example, if the control selector 231 is set toone of the 15 frames per second terminals d, e, the shutter open orstart trigger signal appearing on the AP conductor 240A is followed twocycles later by a shutter closed signal on the AP conductor 246A.

This same relationship is true in the lateral control portion of theselector 230. A start trigger signal appearing on the conductor 240L toclose the electronic contactor and to open the electronic shutter (imagetube 47L) will be followed by a shutter closed signal on the conductor246L by the number of cycles required to provide the desired frame rate.

Also, if terminals b-k are selected, a start trigger signal on thelateral conductor 240L will follow a start trigger signal on the APconductor 240A by the same delay. For example, with the 15 frame ratesettings, the start trigger signal on conductor 240L will follow thestart trigger signal on the AP conductor 240A by two cycles. Thus, whenthe AP control system closes its electronic contactor 27A to energizethe X-ray tube 25A and opens the electronic shutter of the AP image tubeto receive radiation from the X-ray tube, the lateral control systemopens its electronic contractor 27L and closes its electronic shutter.When the lateral control system closes its electronic contactor 27L andopens its electronic shutter, the AP control system closes itselectronic shutter and opens its electronic contactor.

The conductors 240A, 240L connect the movable contacts 238a, 238d to theinputs of normally oif AP and lateral gates 241A, 241L, respectively.The ouputs of the AP and lateral gates 241A, 241L are connected to the=first inputs of AP and lateral shutter flip-flop circuits 243A, 243L,respectively. Control inputs of the gates 241A, 241L are connectable toan energizing source E through lock-in gates 244A, 244L and normallyopen, foot controlled AP and lateral exposure initiating switches 245A,245L, respectively.

The lock-in gates 244A, 244L comprise normally closed control relaycontacts 223A, 223L in series with the foot switches 245A, 245L and thecontrol inputs of the gates 241A, 241L. Control relay coils 244A, 244Lare connected to voltage sources E through foot switches 245A, 245L andto ground connections through controlled rectifiers 225A, 225L. Controlelectrodes of the controlled rectifiers 225A, 225L are connected to thefirst outputs of exposure control flip-flops 251A, 251L via conductors255A, 255L and through single frame selector switches 256A, 256L.

The second inputs of the shutter flip-flops 243A, 243L are connected viaconductors 246A, 246L to the movable contacts 238b and 2382 of theshutter closed switches 230b, 230e. The first and second output of theshutter flip-flops 243A, 243L are connected via conductors 247A, 247L,248A, 248L to the inputs of an OR circuit 249. Conductors 250A, 250Lconnect the second outputs of the shutter flip-flops 243A, 243L to thefirst inputs of the X-ray exposure control flip-flops 251A, 251L. Thesecond inputs of the X-ray exposure control flip-flops 251A, 251L areconnected via conductors 252A, 252L to the movable contacts 238e, 2381of the exposure stop switches 2300, 230f. The second outputs of theX-ray exposure control flip-flops 251A, 251L are connected to the inputsof the multivibrators 54A, 54L via conductors 55A, 55L.

The output of the OR circuit 249 is connected via a conductor 257 to theinput of a shutter delay single shot multivibrator 258. The function ofthe single shot multivibrator 258 is to delay a signal provided at itsoutput at conductor 259 in response to a signal introduced to its inputvia conductor 257. The delay compensates for the slowness inherent inthe high voltage transformation system as compared to the quickness ofthe shutter system. By this delay, the electronic shutters are made tooperate precisely with energization of their respective X-ray tubes. Thelength of the delay is adjusted as is indicated schematically by ashutter delay adjustment control element 260.

The output of the multivibrator 258 is selectively connected to thefirst and second inputs of a final output flip-flop 262 through eitherone of two normally off gates 263, 264. The control inputs of thenormally off gates 263, 262 are connected via conductors 265, 266 to themovable contacts 238a, 238b of the start trigger switch 230A and theshutter closed switch 230b, respectively. The gate 263 is turned on by acontrol pulse appearing on conductor 240A and causes trigger pulses topass only to the first input of the final output flip-flop 262 while acontrol signal appears on conductor 240A. The gate 264 is turned on by acontrol pulse on conductor 246A and causes control pulses to pass onlyto be second input of the final output flip-flop 262 while a controlsignal is on conductor 264A. The output of the final output flip-flop262 is connected by the control conductor 61 to the shutter and cameracontrol circuit 260. An input pulse passed by the gate 263 to the firstinput of the final output fiip-flop 262 will cause the final outputflipfiop to switch its state and connect the conductor 61 to apredetermined negative voltage source. An input pulse passed by the gate264 to the second input of the final output flip-flop 262 will flip theflip-flop 262 into its other stable state wherein the voltage level onthe conductor 61 is at a zero voltage level and above the predeterminedlevel of the negative voltage source.

Referring now to FIGURE 5, the image amplifier tubes 47A, 47Lrespectively include photocathode elements 301A, 301L, focus elements302A, 302L and anode elements 303A, 303L. The image amplifier tubes arepreferably image tubes manufactured by Rauland Company and designated bypart No. R-6l75. In these image tubes the photocathode is a layer on theinside of an input window having also an X-ray sensitive, lightproducing input phosphor layer. The anode element is the outputphosphor. A coating on the inside of the image tube envelope is used asthe focus element 302. The image amplifier tubes 47A, 47L are isolatedfrom ground potential. The coatings on the envelopes of the image tubeswhich are represented by the focus electrodes 302A, 302L are connectedto adjustment taps of focus control potentiometers 305A, 305Lrespectively. The anode elements 303A, 303L are connected to positive 33kilovolt supplies. The focus control potentiometers 305A, 305L areconnected to positive 680 volt supplies which place the focus electrodesat about 600 volts positive to ground. The photocathodes 301A, 301L areconnected to ground point 306 via conductors 307A, 307L and throughdiodes 308A, 308L having their anodes connected to the ground point 306.The conductors 63A, 62L from the outputs of the high voltage flip-flopcircuit 71 are connected to the conductors 307A, 307L at voltage points309A, 309L between the photocathodes 301A, 301L and the diodes 308A,308L.

The switching amplifier 70 comprises a double triode tube having twotriode sections 318, 319. The plates of the triode sections 318, 319 areconnected to the conductors 72, 73 respectively. The control grid of thetriode section 318 is connected to the input control conductor 61through a resistor 320 and its cathode is connected to ground. Thetriode section 319 has its control grid element connected to a minus 10volts through a resistor 319 and its cathode element connected directlyto the control conductor 61. This arrangement of the triode sections318, 319 is such that when the voltage level on the control conductor 61is substantially at zero, the

triode section 318 is turned on and conducts to connect the conductor 72effectively to ground and the triode section 319 is turned off. When thevoltage on the conductor 61 is at a predetermined negative level, thenthe triode section 318 is turned otf and the triode section 319 isturned on and connects the conductor 73 effectively to ground.Connecting either of the conductors 72, 73 to ground provides negativevoltage excursions on them which are integrated by capacitors 313, 314to form negative trigger pulses for operating the high voltage flipfiop71.

The high voltage flip-flop 71 includes two high voltage power tubes 311,312, for example, 6293 tubes. The output square wave voltages from thetubes 311, 312 are, for example, 1300 volts, and are sutficientlypowerful to maintain the shape of the square waves over several feet ofcoaxial cable connecting the control circuit 60 to the image amplifiertubes 47A, 47L.

The high voltage tubes 311, 312 are arranged in a conventional flip-flopcircuit as shown. When one high voltage tube is on the other highvoltage tube is ofif. The operating condition of the flip-flop 71 issuch that when a negative voltage excursion appears on conductor 72 fromamplifier-'70, the resulting trigger pulse passed by the capacitor 313turns the tube 312 on and the tube 311 off. When a negative voltageexcursion appears on the conductor 73, the'resulting negative triggerpulse passed by the capacitor 314 turns the voltage tube 311 on and thevoltage tube 312 off.

The plates of the high voltage tubes 311, 312 are connected as theoutputs of the flip-flop 71 to the voltage points 309A, 309L,respectively. Each of the voltage points 309A, 309L is at approximately1300 volts positive when its associated high voltage tube is turned offin the flip-flop circuit 71. When a voltage point is at a positive 1300volts, the photocathode of the associated image amplifier tube is muchmore positive than the focus electrode and the image amplifier tube isturned off so that no electrons move from its photocathode to its anode.Positive potentials at the voltage points 309A, 309L also reverse biasthe diodes 308A, 308L so that conduction through the diodes is blockedand the photocathodes remain 1300 volts positive relative to the groundpoint 306. When a high voltage tube is turned on in the flip-flopcircuit 71, the associated voltage point 309A or 309L is driven to anegative voltage and forward biases its associated diode 308A or 308L.The forward biased diode clamps its photocathode to ground. Thephotocathode is then at substantially zero voltage level relative to thefocus electrode thereby causing an electron flow to the anode element.In this condition, the image amplifier tube is on and the electronicshutter provided by that image tube is described as open. When one imagetube is on, the 33 kilovolts potential between its cathode and anodeelements accelerates the moving electrons and thereby intensifies theimage on the output phosphor. Acceleration rings or electrodes are alsosuitably provided for image intensifiication purposes.

Because the AP and lateral cameras 48A, 48L and the camera clutchtrigger circuits 75A, 75L are identical, the operating parts of the APcamera and AP clutch trigger circuit only are shown schematically inFIGURE 5. Each cine camera is a suitable clutch operated camera similarto a movie camera, but not having a shutter. A suitable camera is aclutch operated camera sold under the designation of Flight ResearchSingle Frame Camera by Giannini 'Schietific Corporation. Each cameracomprises a motor 320A having a set of two pole windings 321A, a set offour pole windings 322A, a rotor 336A and an output shaft 337A. Thewindings 321A, 322A are energizable across conductors 323A, 324Aconnected to a voltage source e via contacts 326A, 327A of a frame rateselector switch relay 328A. The relay 328A includes a coil 329A which isenergizable from the voltage source e by closure of a 60 frames persecond selector switch 330A. The selector switch 330A is closed by theselector switch 230 when the selector switch indicator 231 is set to the60 frame rate terminal a. The contacts 326A, 327A in their normallyclosed position shown are connected to conductors 331A, 332A and connectone of the two pole windings 321A directly across the voltage source eand the other two pole Winding across the voltage source 8 through aphase splitting capacitor 333A. The two pole windings are energized tocause the rotor 36A and output shaft 337A to rotate at 3600 r.p.m. whenvoltage source e is provided by a main switch (not shown). Closure ofthe switch 330A energizes the coil 329A to move the contacts 326A, 327Ato connect the conductors 334A, 335A to the supply conductor 324A,thereby connecting one of the four pole windings 3 22A across thevoltage source 2 and the other four pole windings across the voltagesource e through the phase splitting capacitor 333A. The energized fourpole Windings cause the rotor 336A and the output shaft 337A of thecamera to rotate at 1800 r.p.m.

The rotor 336A has its output shaft 337A connected to one part of aclutch 338A. The other part of the clutch 338A is connected to a filmtransport drive shaft 339A. As the motor shaft 337A rotates, the shaft339A follows its rotation because the clutch parts are in engagement.The shaft 339A drives a film transport wheel 340A which transports afilm 341A. A single frame stop 342A projects from the shaft 339A and ispositioned to strike a clutch latch 343A as the shaft 339A rotates.

Engagement of the latch 343A by the stop 342A prevents rotation of theshaft 339A by virtue of slippage in the clutch 338A even though themotor shaft 337A continues rotating. Retraction of the latch 343A by acoil 350A against the bias of a spring (not shown) will permit the filmtransport shaft 339A to again rotate thereby tr-an'sporting the film341A. One rotation of the shaft 339A represents one frame in the film341A.

Energization of the coil 350A is controlled by the AP clutch triggercircuit 75A, a normally closed contact 352A of the relay 350A, and anormally open contact 353A operated by a control relay coil 354A. Thecoil 354A is energized to close contact 353A by closure of a secondcontact 245A of the foot switch 245A (FIGURE 2) which connects the coil354A across the voltage source 6. Contact 352A is normally closed andopens to break the energization circuit when the coil 350A is energized.The energization circuit for the clutching coil 350A is completed when athyratron tube 360A in the camera clutch trigger circuit 75A is biasedto a state of conduction. The thyratron tube is normally biased in acut-off condition by the negative bias on conductor 364A in the circuitshown. A positive voltage excursion appears on the conductor 74A whenthe triode section 318 turns off. The positive voltage excursion isintegrated by capacitor 363A. The resulting trigger pulse biases thethyratron tube 360A to a state of conduction connecting the conductor63A and the conductor 355A effectively across the rectified voltagesource 2.

The energized relay coil 350A retracts the latch 343 thereby allowingthe shaft 339A to rotate and transport the .film. Movement of thearmature of the relay 350A also opens the normally closed contacts 252Athereby breaking the energization circuit for the coil 350A. The latch343A returns to its latching position under the infiuence of a biasspring (not shown) so as to engage the stop 342A when it completes onerevolution thereby permitting the shaft 339A to transport the film oneframe position only. This system thus makes one frame of film availablefor exposure for each trigger pulse introduced to the clutch triggercircuit 75A via conductor 74A.

Continuous transportation of the film 341A is required for 60 and 30frame selections. Normally open contacts 357A and 358A are connectedacross the contact 352A and are closed to by-pass contact 352A tomaintain energization of the clutching coil 350A. This causes free rota-14 tion of the shaft 339A at either 1800 r.p.m. or 3600 r.p.m. totransport the film at either 30 frames per second or 60 frames persecond, respectively. The contact 357A is closed by energization of thecoil 329A of the 60 frame rate selection relay 328A. Contact 358A isclosed by energization of the relay coil 359A across the Voltage sourcee by closure of a switch 361A. The frame rate selection switches 330A,361A are operated by the selector 231 (FIGURE 3). The switch 330A closeswhen the selector is positioned to the 60 frame rate terminal a. Theswitch 361A closes when the selector 321 is positioned to either one ofthe 30 frame rate terminals b, e.

60 frames per second operation The X-ray system is set to provide 60frames per second, biplane operation with half cycle exposure times bymoving the indicator 231 to the a terminal on the panel 230 (FIGURE 4).The selector switch 236 is moved to the cine position so that contacts238a238f engage fixed contacts 235a-235f. Moving the indicator 231 tothe a terminal closes the 60 frames per second selector switches 330A,330L in the AP and lateral cameras (FIGURE 5 and opens the bridgerectifier switch in the A-P energization circuit and opens the bridgecircuit selector switch 126 in the lateral X-ray tube energizationcircuit. The power supplies e and E are provided by closing suitablemain controls (not shown). The camera motors cause their output shafts337A, 337L to rotate at 3600 r.p.m. The film transport shafts 339A, 339Lremain stationary by reason of the stops 342A, 342L engaging the latches343A, 343L.

The X-ray exposures are initiated by closing the foot switches 245A,245L so that the gates 241A, 241L are turned ON and the gates 234A, 234Lare turned off. The next trigger pulse on conductors 207, 209 is passedto the first input of the shutter flip-flops 243A, 243L via movableselector switches 231a, 231a, contacts 235a, 235d, 238a, 238d,conductors 240a, 2401, and the gates 241A, 241L which are now turned on.

The start trigger signals provided to the first inputs of the shutterflip-flops 243A, 243L turn the second outputs of these shuttersflip-flops on to provide output signals on the conductors 248A, 248L,250A, 250L to the inputs of the OR circuit 249 and to the first inputsof the exposure time control flip-flops 251A, 251L.

Since the output signals appearing on the conductors 248A, 248L areprovided simultaneously to the OR circuit 249, the OR circuit providesone output signal on its output conductor 257 to the input of the singleshot multivibrator 258. The single shot multivibrator 258 delays thissignal and provides a corresponding delayed signal on its outputconnected to the conductor 259 and then to the input of normally offgates 263, 264. Gate 263 is now on or open by reason of the starttrigger signal being also introduced to its control input via conductors265, 240A. The signal at the input of the gate 263 is introduced to thesecond input of the final output flip-flop 262 which increased thevoltage level on the conductor 61 from a negative potential to a zerovoltage in response thereto. The increase in the voltage level on theconductor 61 turns the triode section 318 on in the amplifier 70 (FIGURE5). The triode section 318 provides a negative excursion on theconductor 72 to turn the high voltage tube 312 otf and the high voltagetube 311 on in the high voltage flip-flop 71. The conducting highvoltage tube 311 causes the photocathode of the AP image tube 47A to beconnected to ground thereby turning the AP image system on.

The start trigger pulses introduced to the first inputs of the exposureflip-flops 251A, 251L by the conductors 250A, 250L turn the secondoutputs of the exposure flip-flops 251A on to provide an energizationinitiation signal on each of the conductors 55A, 55L. The energizationinitiation signals turn the multivibrators 54A, 54L on which in turncause the thyratron tubes 40, 41 in each of the electronic contactors27A, 27L to connect their respective transformers 28 to the supplysource e. Because the bridge rectifier circuits A, 35L in each of thesystems have only two of their rectifier tubes turned on, then only halfwave rectified voltage is provided to the X-ray tubes 25A, 25L. The APX-ray tube 25A is energized by the positive half cycles of the sourcevoltage e and the lateral X-ray tubes 25L is energized by the negativehalf cycles of the input source voltage 2. The A-P and lateral X-raytubes are, therefore, energized in an alternate, biplane relation aslong as the first outputs of the exposure flip-flops 251A, 251L remainon and consequently the electronic contactors 27A, 27L remain on.

At the time the foot switches 245A, 245L were closed, a positive halfcycle of the incoming line voltage e on line 201 resulted in the squarewave output pulse on conductors 207, 209. A negative half cycle of theincoming line voltage e causes an output square wave pulse from theSchmitt trigger on conductors 206, 208. The latter signal pulse isintroduced to the second inputs of the shutter flip-flops 243A, 243L viathe conductors 206, 208, contacts 235b, 235e, 238b, 238s and conductors246A, 246L. The shutter flip-flops 243A, 243L turn on their firstoutputs and turn off their second outputs so that control signals appearon conductors 247A, 247L and are introduced simultaneously to the inputof the OR circuit 249. This control signal is again delayed by thesingle shot multivibrator 258 and is introduced to the inputs of thegating circuit 263, 264. At this time, the gate 264 is opened by reasonof the signal on conductors 266, 246 so that an input signal isintroduced to the second input of the final output flip-flop 262. Thefinal output flip-flop 262 decreases the level of the voltage on theconductor 61 to the amplifier 70. This decrease in voltage level turnsthe triode section 318 off and the triode section 319 on in theamplifier 7 0. Consequently, the high voltage tube 311 is turned 01f,the high voltage tube 312 is turned on, the AP image amplifier 47A isturned off and the lateral image amplifier tube 47L is turned on. Whenthe triode section 318 turns off in the amplifier 70, a positive triggerpulse is applied to the control grid of the thyratron tube 360A in theAP camera clutch trigger circuit 75A, to energize the clutching coil350A, thereby releasing the latch stop 342A. The film transport shaft339A moves the film 341A through the magnetic clutch 338A. The contact357A is closed by reason of closure of the switch 330A and energizationof the coil 329A so that the clutching coil 350A is sealed in andremains energized and the shaft 339A continues to transport film untileither the switch 330A is opened or the motor supply source e is turnedOFF as when the entire system is shut down.

The gates 234A, 234L are turned off by reason of the control voltage onthe conductors 233A, 233L and prevent the passage of an exposure stopsignal to the second inputs of the exposure flip-flops 251A, 251L. Thesecond outputs of the exposure flip-flops 251A, 251L therefore remain onto maintain the multivibrators 54A, 54L on and the X-ray tubes 25A, 25Lconnected for continuous alternate energization in the biplane relation.

The next signal pulse on the conductors 207, 209 passes through thestart switches 230a, 230d, the gates 241A, 241L, the shutter flip-flops243A, 243L, the OR circuit 249 and into the first input of the finaloutput flipflop 262 via the gate 263. The final output flip-fiop 262increases the voltage level on the conductor 61 to turn the AP imagetube system on and the laternal image tube system off. The lateral filmtransport mechanism is actuated when the internal image tube is turnedoff to release a corresponding latch stop 342L (not shown) in thelateral clutch trigger circuit 75L which is also held or sealed in itsrelease position by a coil 350L (not shown) until the system iscompletely shut down.

At this point, the film in both cameras is being transported at the rateof 60 frames per second. The X-ray tubes are being alternately energized60 times per second for half cycle exposure periods each. The nextsucceeding wave signals alternatively provided to the conductors 207,206 from the outputs of the Schmitt trigger 205 alternately increase anddecrease the voltage level on conductor 61. Each increase in voltageturns the A-P image tube on and turns the lateral image tube off. Eachdecrease in the voltage level on conductor 61 turns the lateral imagetube system on and the A-P tube off.

The operation of the electronic contactors 27A, 27L which controlenergization of the X-ray tubes 25A, 25L must be properly phased tooperation of the frame rate and exposure time selector control circuit58 so that one X-ray tube is energized when its associated image tube isturned on as a shutter and the other image tube is turned off.Coincident phasing of the operation of the shutters to the operation ofthe electronic contactors is substantially provided by using the samevoltage source e throughout the two X-ray systems 22, 23. Adjustments inphasing the operation of the selector system 58 to the energizationcircuits for the X-ray tubes, both of which are supplied by the samevoltage source "e to maintain synchronism is he means of the phaseadjusting element 203 in the phase shift circuit 202. The delayadjustment element 260 of the single shot multivibrator 258 adjusts theamount of delay required to delay operation of the image amplifier tubesas shutters relative to the operation of the electronic contactors tocompensate for inherent delays in the transformation systems in theX-ray tube energization circuits.

When an exposure is terminated by releasing the foot switches 245A,245L, the gates 241A, 241L are turned off to prevent any further starttrigger signals reaching the first inputs of the shutter flip-flops243A. However, a signal pulse on conductors 206, 208 from the firstoutput of the Schmitt trigger 205 is still conveyed to the second inputsof the shutter flip-flops 243A, 243L so that a lateral exposure isalways the last or final exposure. Releasing the foot switches 245A,245L turns the gates 234A, 234L on so that the next output signal pulseon the conductor 207, 209 is introduced to the second inputs of theexposure control flip-flops 251A, 251L via the contacts 231e, 2311,235e, 235 conductors 252A, 252L. The exposure control flip-flops 251A,251L then turn off their second outputs and turn on their first outputsso that the electronic contactors are de-energized to open theenergization circuits for the X-ray tubes for further energization afterthe lateral exposure is made.

Positioning the OV-TV cine selector contact 238a, 238 to engage theOV-TV contact 237a-237f also provides for 60 frames per second, halfcycle exposure operation of the AP and lateral X-ray tube systems 22,23. In addition, the selector switch 236 sets up a television systemand/ or an optical viewing piece selectively for viewing the outputphosphors of the image amplifier tubes 47A, 47L, instead of the cinecameras 48A, 48L.

30 frames per second operation Moving the indicator 231 to either of the30 frame rate terminals b, c closes the switches 361A, 361L to energizerelays 359A, 359L and close contacts 358A, 358L in the A-P and lateralcamera circuits (again, only the AP components are shown in FIGURE 5)The film transport motors are then caused to rotate their output shaftsat 1800 r.p.m. which will provide 30 frames per second transportation ofthe films 341A, 341L when the clutch coils 350A, 350L are energized torelease the latch stops 342A, 342L. The closed contacts 358A, 358L willseal in the clutching coils 350A, 350L so that film transportation iscontinuous once initiated.

Closing the exposure initiating foot switches 245A, 245L permits a starttrigger signal on conductor 216 to pass through the start trigger switch230a to the first input of the shutter flip-flop 243A via the selectorcontact 231a, contacts 235a, 238a, conductors 240A and the gate 241A.

The same signal on the conductor 216 is also introduced into the lateralportion of the selector circuit 58 by the lateral shutter closedselector switch 230e to the second input of the lateral shutterflip-flop 243L and by the exposure stop selector switch 230 to thesecond input of the exposure flip-flop 251L. The second output of the APshutter flip-flop 243A and the first output of the lateral shutterflip-flop 243L are turned on. The control signals appearing on theconductors 248A and 248L from the flip-flops 243A, 243L are introducedsimultaneously to the R circuit 249 which produces a single signal tothe multivibrator 258 which results in a delayed signal being introducedto the inputs of the gate circuits 263, 264. The gate 263 is on sincethe conductors 265A, 240A are energized and passes the input signal tothe first input of the final output flip-flop 262 to increase thevoltage level on the control conductor 61. The signal at the secondoutput of the shutter flip-flop 243A is also introduced to the firstinput of the exposure control flip-flop 251A which turns the electroniccontactor 27A on in the A-P circuit. The increase in voltage level onthe conductor 61 turns the A-P image tube shutter system on for an A-Pexposure.

One cycle later, a signal appears on the conductor 217 from the Schmitttrigger 211 and is introduced by the shutter closed selector switch 23Gbto the second input of the shutter flip-flop 243A in the A-P system andto the first input of the lateral shutter flip-flop 24-3L in the lateralsystem. If the selector contacts 231a-231f are at the b terminals thenthe exposure stop selector switch 230v introduces the same signal onconductor 217 as a stop signal to the second input of the exposuretermination flipflop 251A to turn off the AP electronic contactor 27A.If the selector switches 231a231f are positioned at the 0 terminals,then the exposure stop selector switch 230 introduces a control signalfrom the conductor 209 as an exposure stop signal to the second input ofthe exposure flipflop 251L a half cycle after the start trigger signalfrom the start trigger signal selector 230a. The shutter closed signalfrom the selector switch 23011 and the start trigger signal from theselector switch 230d cause a single signal to be produced by the ORcircuit 249 to the second input of the final output flip-flop 262through gate 264 since the conductor 266 is energized. This results in adecrease in the voltage level on the conductor 61 to turn the lateralimage tube system on and the A-P image tube system off. One cycle later,another output signal appears on the conductor 216 to turn the A-Pshutter system on and to turn the lateral shutter system off. If theselector switch 230 is at the terminal b, the same signal causes the A-PX-ray tube to be energized and the lateral X-ray tube to bede-energized. The lateral camera is also sealed in and running, therebytransporting its film continuously at 30 frames per second. As long asthe foot switches 245A, 245L are closed the system continues to run withthe shutters provided by the image tubes being turned on alternately atthe rate of 30 exposures per second each so as to expose each adjacentframe of the films in the cameras. The electronic contactors are openedand closed 30 times a second to provide 30 X-ray exposures per secondfrom their respective X-ray tubes in synchronized relation with theimage tubes. Opening the exposure initiating switches 245A, 245Lprevents a further start trigger signal being introduced to the shutterflip-fiops 243A, 243L and also to the exposure control flip-flops 251A,251L. The system makes a final lateral exposure and then stops.

15 and 7 /2 frames per second Operation The operation of the system forthe 15 and 7 /2 frame rate settings is substantially identical to the 30frame rate setting just described except that the film transportmechanism is not continuously running. In the 15 and 7 /2 frames persecond settings, the contacts 357, 358 remain open and the coils 350A,350 L are de-energized immediately after each energization by contacts352A, 352L to relatch the film transport shafts 339A, 339L. In the 7 /2and 15 frame rate settings, therefore, the shafts 339A,

18 339L make one revolution only for each input trigger pulse suppliedto each of the clutch trigger circuits 75A, 75L and thereby position asingle frame for exposure. In these two frame rate settings, therefore,each time an image tube system is turned off, its film is transportedone frame position only and then stops.

If one of the 15 frame rate terminals d or e are selected, then theshutter closed signals introduced to the second inputs of the shutterflip-flops are two cycles behind the start trigger signals introduced tothe first inputs of the shutter flip-flops. The exposure terminationsignals introduced to the second inputs of the exposure flip-flops arethen two cycles behind the start trigger signals if terminal d isselected and a half cycle behind if terminal e is selected. In the 7 /2frame rate setting, the shutter closed signals are four cycles behindthe start trigger signals. The exposure stop or termination signals arefour cycles behind the start trigger signals for the terminal 1 and ahalf cycle behind it terminal g is selected.

Single frame operation Single frame exposures are provided by closingthe switches 256A, 256L. W-hen switches 256A, 256L are closed, outputsignals at the number two outputs of the exposure control flip-flops251A, 251L bias the controlled rectifiers 225A, 225L to conduct andenergize the control relays 224A, 224L to open their contacts 223A,223'L. The open contacts 23A, 23L turn oil? the gates 241A, 2'41L andprevent the transmission of start trigger signals to the shutterflip-flops 243A, 2*43L. The contacts 223A, 223L remain held open untilthe foot switches are released to open. Subsequent reclosure of the footswitches again biases the gates 241A, 241L to pass another startingtrigger pulse to each of the shutter flip-flops 243A, 2431s. Thus, thegates 241A, 24111 are turned on by initial closure of the foot switches254A, 254L to pass one start trigger pulse each and are turned off by anexposure termination pulse and held off by the locking gates 244A, 244Luntil the foot switches are released, thereby permitting a singleexposure on y.

Although the invention 'has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by wayof example andthat numerous changes in the details of construction and the combinationand arrangement of parts may be resorted to without departing from thespirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. An X-ray system comprising:

(a) an X-ray tube for providing X-ray to a subject;

(b) supply means for selectively energizing said X-ray tube, andincluding an electronic contactor for selectively connecting anddisconnecting said X-ray tube and a supply source;

(c) an image amplifier tube having:

(i) input window means receiving an X-ray image from the subjectX-rayed,

(ii) said input window means including cathode means for emittingelectrons in the received image,

(iii) output window means for receiving said electrons and providing anoutput image, and

(iv) control means between said cathode means and said output windowmeans;

((1) bias means for biasing said output window means and said controlmeans to enhance the flow of electrons toward said output window meansand for biasing said cathode means relative to said control means so asto prevent the flow of electrons from said cathode means toward saidoutput window means;

(e) switch means connected to said bias means and to said cathode meansfor selectively connecting said cathode means to a bias potential thatis positive relative to a bias potential on said control means toprevent thereby said flow of electrons, and for selectively connectingsaid cathode means to a potential that is negative relative to said biaspotential on said control means thereby to permit said flow ofelectrons; and

(f) exposure time control means connected to said electronic contactorand to said switch means, said exposure time control means causing saidelectronic contactor to connect said X-ray tube to said supply sourcewhen said switch means connects said cathode means to the relativelynegative potential and to disconnect said X-ray tube from said supplysource when said switch means connects said cathode means to therelatively positive potential after a preselected exposure period.

2. The system of claim 1 wherein said exposure time control meansincludes means to initiate a preselected exposure period by causing saidswitch means to connect said cathode means to said ground referencepotential for said predetermined period and by causing said electroniccontactor to connect said X-ray tube to said supply source for saidpreselected period.

3. The system of claim 2 wherein said exposure time control meansincludes delay means to delay initiation of the operation of said switchmeans relative to the operation of said electronic contactor.

4. The system of claim 3 including:

(g) a shutterless camera focused in light tight relation on said outputmeans so that a film in the camera is exposed for a period that theelectrons fiow to the output window means from the cathode means; and,

(h) said camera having film transport means connected to said switchmeans and transporting an unexposed film portion into the cameras fieldwhen the bias of the cathode means relative to the control means ischanged to prevent the flow of electrons to said output window means.

5. In an X-ray system having a plurality of X-ray tubes for providingX-rays to a subject from different angles and image amplifier tubes forreceiving X-ray images on their input windows and displaying intensifiedimages on their output windows, a control system comprising:

(a) a plurality of X-ray tube energization circuits for energizationsaid X-ray tubes for the duration of energization control signalsreceived at their inputs;

(b) a plurality of image tube shutter circuits connected to said imagetubes and normally being turned OFF and maintaining said image tubes inan offbiased condition wherein an image received at its input window isprevented from being intensified and transmitted to its output windowfor display purposes, each said shutter control circuit when turned ONchanging the bias on its respective image tube in response to an ONsignal to permit the intensification of a received image andtransmission of it to its output window for the duration of said Nsignal and thereby turning its image tube ON;

(c) switching means connected to each of said shutter control circuitsand assuring that one shutter control circuit is turned OFF when theother shutter control circuit is turned ON; and,

(d) exposure control means connected to said shutter control circuitsand to said energization circuits for energizing one X-ray tube when itsrespective image amplifier tube is ON while maintaining the other X-raytube de-energized, and for energizing the other X-ray when itsrespective image amplifier tube is ON while maintaining said one X-raytube de-energized.

6. The combination of claim 5 wherein said switching means comprises ahigh voltage flip-flop having first and second outputs, one shuttercontrol circuit is connected to said first output and the other shuttercontrol circuit is connected to said second output.

7. The system of claim 5 wherein each of said shutter control circuitsincludes a first circuit means connecting a photocathode of the inputwindow of its associated image amplifier tube to a positive potential tonormally maintain said image amplifier tube turned OFF and a secondcircuit means connecting said photocathode to effectively zero potentialwhen said shutter control circuit is turned ON by said switching means.

8. The system of claim 6 wherein each of said shutter control circuitsincludes a first circuit means connecting a photocathode of the inputWindow of its associated image amplifier tube to a positive potential tonormally maintain said image amplifier tube turned OFF and a secondcircuit means connecting said photocathode to effectively zero potentialwhen its respective output of the flip-flop is turned ON.

9. The system of claim 5 wherein said exposure control circuit includesexposure time means for selecting the duration of the energizationcontrol signals provided to the X-ray tube energization circuits therebyselecting exposure periods.

10. The system of claim 5 wherein said switching circuit turns saidshutter control circuits ON alternately in response to successivetrigger signals provided to said switching means and said exposurecontrol means includes frame rate selection means for selecting thefrequency of trigger signals provided to said switching means and forselecting the frequency of said energization control signals provided tosaid energization control circuits whereby the frequency of the X-rayexposures may be selected.

11. The system of claim 9 wherein said switching circuit turns saidshutter control circuits ON alternately in response to successivetrigger signals provided to said switching means and said exposurecontrol means includes frame rate selection means for selecting thefrequency of trigger signals provided to said switching means and forselecting the frequency of said energization control signals provided tosaid energization control circuits whereby the frequency of the X-rayexposures may be selected.

12. The system of claim 11 wherein said exposure control means includesdelay means for delaying the trigger signals relative to theenergization control signals so as to compensate for delays in theenergization circuits so that the energization of the X-ray tubescoincides exactly with turning on the associated image tube.

13. The system of claim 12 including:

(e) a shutterless cine camera for each image tube, said camera beingfocused in light tight relation on the output window of its imageamplifier tubes.

14. The system of claim 13 wherein each of said cameras include filmtransport means connected to said shutter control means for transportingan unexposed portion of film into an exposure position when itsrespective image amplifier tube is turned OFF.

15. A biplane system comprising:

(a) AP and lateral X-ray tubes arranged to emit beams of X-rays atdifferent angles to a subject;

(b) AP and lateral energization circuits connected to said AP andlateral X-ray tubes respectively for selectively energizing the X-raytubes in response to energization initiation signals for the period ofsaid signals;

(c) AP and lateral image amplifier tubes associated with said AP andlateral X-ray tubes respectively, each image amplifier tube having:

(i) an input window disposed to receive X-rays from its associated X-raytube in the image of the subject X-rayed at the angle X-rayed;

(ii) intensification means for intensifying the image received at theinput window;

(iii) an output window for displaying the intensified image; and,

(iv) image transmission control means for selec- 21 tively permittingand preventing the transfer and intensification of the image from theinput window to the output window;

(d) AP and lateral shutter control means connected to (e) switchingmeans connected to each of said shutter control means, said switchingmeans having alternate first and second states and switching from onestate to the other in response to a trigger input signal, said switchingmeans in said first state causing said AP shutter control means to biasthe image transmission control means of its respective AP image tube topermit the intensitfication and transmission of the image to the outputwindow for the period that said switching means is in said first state,said switching means in said second state causing said lateral shuttercontrol means to bias the image transmission control means of thelateral image tube so as to permit the intensification and transmissionof the received image to its output window for the period that saidswitching means is in said second state, and said switching meanspreventing intensification and transmission within the AP and lateralimage tubes when said switching means is in its second and first statesrespectively;

('f) exposure control means connected to said switching (g) saidswitching means providing successive signals to said X-ray tubeenergization circuits to cause said AP energization circuit to energizesaid AP X-ray tube when said switching means is in said first state andto cause said lateral energization circuit to energize said lateralX-ray tube when said switching means is in said second state wherebytransmission and intensification of images within the AP and lateralimage amplifier tubes is prevented when the lateral and AP X-ray tubesare energized respectively.

16. The system of claim 15 wherein said switching means comprises a highvoltage flip-flop having first and second outputs, one shutter controlmeans is connected to said first output and the other shutter controlmeans is connected to said second output.

17. The system of claim 16 wherein each of said shutter control meansincludes a first circuit means connecting a photocathode of the inputwindow of its associated image amplifier tube to a positive potential tonormally maintain said image amplifier tube turned OFF and secondcircuit means connecting said photocathode to effectively zero potentialwhen said shutter control means is turned ON by said switching means.

References Cited UNITED STATES PATENTS 1,950,764 3/1934 Wantz 250-942,790,085 4/1957 Fransen et al. 250- 2,809,296 10/1957 Godbarsen 250952,853,619 9/1958 DeWitt 250-65 3,130,346 4/1964 Callick 31522 FOREIGNPATENTS 692,985 6/1953 Great Britain.

RALPH G. N-ILSON, Primary Examiner.

S. C. SHEAR, Assistant Examiner.

U.S. Cl. X.R. 250-65 ro-wso Patent No.

Dated April 22, 1969 Inventor) Jack Ball and Gunter G. wilkens It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 2, delete "brighteness" substitute brightness- Column 6,line 1, delete at end of line.

Column 10, line 32, delete "contractor" substitute contactor-- Column11, line 22, delete "be" substitute the line 58, delete "63A" substitute62A line 72, delete "319" substitute 319 Column l2, line 67, delete"Schietific" substitute Scientific-- Column 13, line 10, delete "36A"substitute 336A Column 18, line 28, delete "23A, 23L" substitute 223A,223L Column 19, line 44 (claim 5) delete "energization" substituteenergizing Column 19, line LAM Edward ll. Flu-1m, Ir.

Anening Officer SIGNED AND SEALED OCTZIMQ WILLIAM E. SGHUYLER, .13.Commissioner or Petunia

